Piezo-resistive sensing of mirror position in an optical switch

摘要

An integrated piezo-resistive sensor for determining mirror position in an optical switch. One or more piezo-resistive layers may be formed in silicon springs supporting a movable mirror in the switch. Change in resistivity of those layers due to spring deformation during mirror motion is measured and related to the mirror deflection angle. Information about the angle may be used to provide feedback to the motion actuator, which then may be operated to orient the mirror more accurately. A sensor's sensitivity may be increased by appropriately orienting the springs with respect to the crystallographic axes of the silicon.